#define  _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>
//#include<string.h>
#include<assert.h>

char* my_strcat(char* dest, const char* source)
{
	char* ret = dest;
	while (*dest) {
		dest++;
	}
	while (*dest++ = *source++) {
		;
	}
	return ret;
}
int main()
{
	char arr1[20] = "abcdf";
	char arr2[10] = "ghijk";
	my_strcat(arr1, arr2);
	printf("%s", arr1);
	return 0;
}